The present invention relates to a fixing tool used to mount an electronic component, a cable, or the like on a board for an electronic device or the like and, more particularly, to a fixing tool which performs fixing by utilizing a mounting hole formed in the board.
When assembling an electronic device, electronic components must be mounted on an assembly board such as a panel, chassis, board, or the like (which will be referred to as a board hereinafter), and an interconnecting component such as a cable must be extended on the board. A fixing tool is used for this purpose. In recent years, regarding home electrical appliances, OA devices, automobiles, and electronic devices as a whole, marketing of products that are friendly to the environment is obliged as a solution to the environmental issues. Along with this demand, the fixing tool must be able to be disassembled from the board. Particularly, to facilitate the disassembling operation, the fixing tool must be to disassembled easily without using any tools. For this purpose, regarding the structure of the fixing tool of this type, a fixing tool which is to be fitted in a hole formed in the board by utilizing its elastic force has been proposed. If the fixing tool is fitted merely by utilizing its elastic force, when an external force larger than the elastic force is applied to it, the fixing tool may undesirably drop from the board.
In order to prevent this dropping of the fixing tool, a fixing tool has been proposed which is fitted in a hole, is then rotated through 90° along the surface of the board, so that it is locked. For example, Japanese Patent Laid-Open No. 2001-82427 proposes a fixing tool 101 as shown in FIG. 14A. In this fixing tool 101, a crisscross mounting hole 103 having a thick notched portion 103a and thin notched portion 103b is formed in a plate member 102. A fixing portion 120 has a wide locking projecting piece 122 and narrow engaging portion 123 that are stacked at the distal end of a leg portion 121 which is to be inserted in the mounting hole 103. A pressing wing portion 124 is formed at the proximal end of the leg portion 121 in a direction perpendicular to the locking projecting piece 122. After the locking projecting piece 122 of the fixing tool 101 is inserted to the lower surface side of the plate member 102 through the thick notched portion 103a, the fixing tool 101 is rotated through 90° along the surface of the plate member 102. Thus, an elastic force is generated as the pressing wing portion 124 abuts against the surface of the plate member 102, causing the locking projecting piece 122 and the engaging portion 123 above it to be fitted in the thin notched portion 103b. Since the plate member 102 is clamped by the locking projecting piece 122 and pressing wing portion 124, the fixing tool 101 can be mounted. In this mounting state, engagement of the locking projecting piece 122 and thin notched portion 103b prevents the fixing tool 101 from disengaging from the plate member 102 by merely pulling the fixing tool 101 to the upper surface side of the plate member 102.
According to the studies by the inventor of the present application, the fixing tool described in this reference has the following problem. More specifically, as shown in FIG. 14B, when an external force that flexes the pressing wing portion 124 is applied to press the fixing tool 101 to the lower surface side of the plate member 102, the locking projecting piece 122 and engaging portion 123 may be undesirably pushed down to below the thin notched portion 103b and be disengaged from it. In this case, when a force in a rotating direction is applied to the fixing tool 101, the locking projecting piece 122 and engaging portion 123 cannot engage with the thin notched portion 103b again. Hence, in this state, the rotational position of the fixing tool 101 is gradually changed by the force in the rotating direction applied to the fixing tool 101. When the locking projecting piece 122 and engaging portion 123 are rotated to correspond to the thick notched portion 103a, the fixing tool 101 is undesirably removed from the mounting hole 103. Therefore, the fixing tool of this reference is not necessarily satisfactory in terms of removal prevention.